Semiconductor device and method of manufacturing a semiconductor device

ABSTRACT

A semiconductor device includes a substrate, a wiring formed on the substrate, an anti-reflection film of titanium nitride formed on the wiring, and a silicon oxide film formed on the anti-reflection film. A pad portion which exposes the wiring is formed at a place where a first opening portion and a second opening portion overlap with each other. A metal nitride region containing fewer dangling bonds is formed from a metal nitride film containing fewer dangling bonds than in the anti-reflection film in at least a part of one or both of an opposed surface of the anti-reflection film which faces the silicon oxide film above the anti-reflection film, and an exposed surface of the anti-reflection film which is exposed in the second opening portion.

RELATED APPLICATIONS

This application is a divisional patent application of U.S. applicationSer. No. 15/918,405, filed Mar. 12, 2018, which claims priority under 35U.S.C. § 119 to Japanese Patent Application No. 2017-048802 filed onMar. 14, 2017, the entire content of which is hereby incorporated byreference.

This application BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device and a method ofmanufacturing a semiconductor device.

2. Description of the Related Art

An existing semiconductor device includes a wiring made of aluminum oran aluminum alloy and formed on a substrate, an anti-reflection filmmade of titanium nitride and formed on the wiring, and an oxide filmformed on the anti-reflection film, and a pad portion which exposes thewiring is formed at a place where an opening portion formed in the oxidefilm and an opening portion formed in the anti-reflection film overlapwith each other in plan view.

In a semiconductor device having such a structure, titanium nitridewhich forms the anti-reflection film is sometimes corroded in a portionsurrounding the opening portion by a long-term reliability test thatinvolves bias application under a high-temperature and high-humidityenvironment, abbreviated as THB (Temperature Humidity Bias).

To solve this problem, a semiconductor device has been proposed in whichtitanium nitride forming the anti-reflection film is not exposed in theopening portion.

For example, in Japanese Patent No. 5443827, there is proposed asemiconductor device including: a first surface protection film with afirst opening portion formed above a pad; and a second surfaceprotection film formed on the pad and the first surface protection filmto have a second opening portion above the pad, in which the padincludes a first conductor film and an anti-reflection film formed onthe first conductor film, the second opening portion is contained in aninner region of the first opening portion, and the anti-reflection filmis removed from the inner region of the first opening portion.

However, in the method described in Japanese Patent No. 5443827, it isrequired to perform a photolithography step twice to form the openingportion for exposing the pad, resulting in increase of the number ofsteps.

In addition, in a semiconductor device of the related art, particularlyone in which a silicon oxide film is formed on an anti-reflection filmmade of titanium nitride, the anti-reflection film may change intotitanium oxide due to the long-term reliability test (THB) that involvesbias application under a high-temperature and high-humidity environment,resulting in a possible impairment of the external appearance of theanti-reflection film.

SUMMARY OF THE INVENTION

The present invention provides a semiconductor device in which titaniumnitride forming an anti-reflection film is resistant to oxidationdespite the presence of a silicon oxide film formed on theanti-reflection film made of titanium nitride, and an opening portionfor exposing a pad portion can be formed by performing aphotolithography step once, and also provides a method of manufacturingthe semiconductor device.

Through extensive research, the inventors of the present invention havethought that a metal nitride region containing fewer dangling bonds thanin the anti-reflection film should be formed in at least a part of oneor both of an opposed surface between an oxide film formed on theanti-reflection film and the anti-reflection film, and an exposedsurface of the anti-reflection film exposed in an opening portion, whichleads to the present invention.

In the following a description “the metal nitride region containingfewer dangling bonds” is frequently used instead of “the metal nitrideregion containing fewer dangling bonds than in the anti-reflection film”to avoid redundancy.

Specifically, the present invention relates to the following items.

According to one embodiment of the present invention, there is provideda semiconductor device including:

a substrate;

a wiring formed on the substrate;

an anti-reflection film formed of titanium nitride on the wiring;

a silicon oxide film formed on the anti-reflection film;

a pad portion-exposing the wiring, and formed at a place where a firstopening portion formed in the silicon oxide film and a second openingportion formed in the anti-reflection film overlap with each other inplan view; and

a metal nitride region containing fewer dangling bonds than in theanti-reflection film formed in at least a part of one or both of anopposed surface of the anti-reflection film facing the silicon oxidefilm above the anti-reflection film, and an exposed surface of theanti-reflection film being exposed in the second opening portion.

According to one embodiment of the present invention, there is provideda method of manufacturing a semiconductor device including:

forming a wiring on a substrate;

forming an anti-reflection film from titanium nitride on the wiring byreactive sputtering that uses argon gas and nitrogen gas;

forming a metal nitride film that contains fewer dangling bonds than inthe anti-reflection film on the anti-reflection film by reactivesputtering in which a proportion of nitrogen gas to argon gas is sethigher than a proportion of nitrogen gas to argon gas that is used whenthe anti-reflection film is formed;

forming a silicon oxide film on the metal nitride film containing fewerdangling bonds; and

forming an opening that penetrates the silicon oxide film, the metalnitride film containing fewer dangling bonds, and the anti-reflectionfilm, and that exposes the wiring at a bottom of the opening.

According to one embodiment of the present invention, there is provideda method of manufacturing a semiconductor device including:

forming a wiring on a substrate;

forming an anti-reflection film from titanium nitride on the wiring;

forming a metal nitride film that contains fewer dangling bonds than inthe anti-reflection film by performing a nitridation process on asurface of the anti-reflection film;

forming a silicon oxide film on the metal nitride film containing fewerdangling bonds; and

forming an opening that penetrates the silicon oxide film, the metalnitride film containing fewer dangling bonds, and the anti-reflectionfilm, and that exposes the wiring at a bottom of the opening.

According to one embodiment of the present invention, there is provideda method of manufacturing a semiconductor device including:

forming a wiring on a substrate;

forming an anti-reflection film from titanium nitride on the wiring;

forming a silicon oxide film on the anti-reflection film;

forming an opening that penetrates the silicon oxide film and theanti-reflection film, and exposes the wiring at a bottom of the opening;and

forming a metal nitride region that contains fewer dangling bonds thanin the anti-reflection film by performing a nitridation process on aportion of the anti-reflection film that is exposed in the opening.

According to the semiconductor device of the present invention, themetal nitride region containing fewer dangling bonds than in theanti-reflection film is formed in at least a part of one or both of theopposed surface of the anti-reflection film which faces the siliconoxide film above the anti-reflection film, and the exposed surface ofthe anti-reflection film which is exposed in the opening portion formedin the anti-reflection film. This makes titanium nitride forming theanti-reflection film resistant to oxidation, thereby giving thesemiconductor device high reliability.

The semiconductor device of the present invention in which the openingportion for exposing the pad portion can be formed by performing aphotolithography step once has excellent productivity as well.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view for illustrating an example of asemiconductor device according to the present invention.

FIG. 2 is a process view for illustrating an example of a method ofmanufacturing the semiconductor device of FIG. 1.

FIG. 3 is a process view for illustrating the example of the method ofmanufacturing the semiconductor device of FIG. 1.

FIG. 4 is a process view for illustrating the example of the method ofmanufacturing the semiconductor device of FIG. 1.

FIG. 5 is a process view for illustrating the example of the method ofmanufacturing the semiconductor device of FIG. 1.

FIG. 6 is a process view for illustrating the example of the method ofmanufacturing the semiconductor device of FIG. 1.

FIG. 7 is a process view for illustrating another example of the methodof manufacturing the semiconductor device of FIG. 1.

FIG. 8 is a process view for illustrating the other example of themethod of manufacturing the semiconductor device of FIG. 1.

FIG. 9 is a schematic sectional view for illustrating another example ofthe semiconductor device according to the present invention.

FIG. 10 is a process view for illustrating an example of a method ofmanufacturing the semiconductor device of FIG. 9.

FIG. 11 is a process view for illustrating the example of the method ofmanufacturing the semiconductor device of FIG. 9.

FIG. 12 is a process view for illustrating the example of the method ofmanufacturing the semiconductor device of FIG. 9.

FIG. 13 is a process view for illustrating the example of the method ofmanufacturing the semiconductor device of FIG. 9.

FIG. 14 is a schematic sectional view for illustrating still anotherexample of the semiconductor device according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The inventors of the present invention have acquired the followingfindings as a result of extensive research.

The inventors of the present invention have examined the corrosion oftitanium nitride caused in a semiconductor device of the related art bya long-term reliability test (THB) that involves bias application undera high-temperature and high-humidity environment. As a result, it hasbeen found that, when an anti-reflection film made of titanium nitrideand a silicon oxide film are formed on a wiring in the stated order, anda pad portion which exposes the wiring is formed at a place where afirst opening portion formed in the silicon oxide film and a secondopening portion formed in the anti-reflection film overlap with eachother in plan view, the oxidation of titanium nitride begins from theside of an opening portion (the second opening portion in Claims) of anopposed surface of the anti-reflection film which faces the siliconoxide film above the anti-reflection film.

Oxidation in the opposed surface of the anti-reflection film which facesthe silicon oxide film above the anti-reflection film is inferred to becaused by reaction between titanium atoms in the anti-reflection filmand moisture passing through the silicon oxide film. Oxidation in anexposed surface of the anti-reflection film which is exposed in thesecond opening portion is inferred to be caused by reaction betweentitanium atoms in the anti-reflection film and moisture infiltratinginto the second opening portion.

In view of this, the inventors of the present invention have made afurther study focused on dangling bonds of titanium atoms in theanti-reflection film. Titanium atoms in the surface of theanti-reflection film made of titanium nitride generally have danglingbonds that are not bonded to nitrogen. Dangling bonds of titanium atomsthat are not bonded to nitrogen have high reactivity, and thus readilyreact with moisture passing through the oxide film, or moistureinfiltrating into the second opening portion.

It is therefore inferred that an effective way to prevent the oxidationof the anti-reflection film made of titanium nitride is to reduce thenumber of dangling bonds of titanium atoms that are present in a readilyoxidized surface of the anti-reflection film and that are not bonded tonitrogen.

The number of dangling bonds of titanium atoms that are not bonded tonitrogen can be reduced by, for example, performing a nitridationprocess on the readily oxidized surface of the anti-reflection film sothat nitrogen atoms are bonded to dangling bonds of titanium atoms thatare not bonded to nitrogen. The thus obtained surface of theanti-reflection film in which the number of dangling bonds of titaniumatoms is reduced is a metal nitride region containing fewer danglingbonds than in the anti-reflection film.

Another way that is inferred to be effective for the prevention of theoxidation of the anti-reflection film made of titanium nitride is toprovide a metal nitride region containing fewer dangling bonds than inthe anti-reflection film on the readily oxidized surface of theanti-reflection film. In this case, it is surmised that the metalnitride region containing fewer dangling bonds hinders reaction betweentitanium atoms in the titanium nitride that are not bonded to nitrogenand moisture that infiltrates from the opening portion and passesthrough the silicon oxide film formed on the anti-reflection film, ormoisture that infiltrates into the second opening portion.

The metal nitride region containing fewer dangling bonds, can be formedof, for example, a nitride obtained by reactive sputtering in which theproportion of nitrogen gas to argon gas is set high. Specific examplesof a nitride that can be formed by reactive sputtering with theproportion of nitrogen gas to argon gas set higher than normal includetitanium nitride, tantalum nitride, molybdenum nitride, and tungstennitride.

The inventors of the present invention have thus found that theoxidation of titanium nitride can be prevented by forming a metalnitride region that contains fewer dangling bonds than in theanti-reflection film in at least a part of one or both of the opposedsurface of the anti-reflection film which faces the silicon oxide filmabove the anti-reflection film, and the exposed surface of theanti-reflection film which is exposed in the second opening portion, tothereby lower the chance of reaction between dangling bonds of titaniumatoms in the anti-reflection film that are not bonded to nitrogen andmoisture passing through the silicon oxide film, or moistureinfiltrating into the second opening portion, and the inventors of thepresent invention consequently have thought of the present invention.

The present invention is described in detail below with reference to thedrawings. Some of the drawings referred to in the following descriptionare enlarged views of characteristic portions which are enlarged forconvenience of making the characteristics of the present inventionunderstood easier, and the ratios of the dimensions of components to oneanother and the like may differ from actuality. The materials,dimensions, and the like given in the following description are anexample, and the present invention is not limited thereto. The presentinvention can be carried out in suitably varied modes without losing theeffects of the present invention.

<First Embodiment>

[Semiconductor Device]

FIG. 1 is a schematic sectional view for illustrating an example of asemiconductor device according to the present invention.

A semiconductor device 10 according to a first embodiment of the presentinvention includes a substrate 1, a wiring 6 formed on the substrate 1with an interlayer insulating film 2 interposed between the substrate 1and the wiring 6, an anti-reflection film 7 formed on the wiring 6, asilicon oxide film 3 formed above the anti-reflection film 7, and aprotection film 4 formed on the silicon oxide film 3.

In the semiconductor device 10 according to the first embodiment, a padportion 8 which exposes the wiring 6 is formed at a place where a firstopening portion 91 which is formed in the silicon oxide film 3, a secondopening portion 92 which is formed in the anti-reflection film 7, and athird opening portion 93 which is formed in the protection film 4,overlap with one another in plan view as illustrated in FIG. 1.

In the semiconductor device 10 of FIG. 1, a metal nitride region 7 acontaining fewer dangling bonds than in the anti-reflection film 7 isformed on the entire opposed surface of the anti-reflection film 7 whichfaces the silicon oxide film 3 above the anti-reflection film 7.

A substrate made of silicon or other known materials can be used as thesubstrate 1.

The interlayer insulating film 2 can be a known insulating film, forexample, a SiO₂ film, or an oxide film having tetraethyl orthosilicate(TEOS) (Si(OC₂H₅)₄) as a raw material.

The silicon oxide film 3 is formed so as to cover the wiring 6 on whichthe anti-reflection film 7 and the metal nitride region 7 a containingfewer dangling bonds, are formed.

Specific examples of a film that can be used as the silicon oxide film 3include a SiO₂ film and an oxide film having TEOS as a raw material.

A preferred thickness of the silicon oxide film 3 is from 2,000 Å to8,000 Å, and a thickness of about 5,000 Å is even more preferred.

The protection film 4 can be a silicon nitride film, a siliconoxynitride film, or a similar film, and a silicon nitride film ispreferred as the protection film 4. In the semiconductor device 10 ofFIG. 1, the silicon oxide film 3 is provided between the protection film4 and the anti-reflection film 7, and hence stress between theprotection film 4 and the anti-reflection film 7 can be lessenedcompared to the case in which the protection film 4 and theanti-reflection film 7 are in contact with each other. As a result, inthe semiconductor device 10 of FIG. 1, fine adhesion between theanti-reflection film 7 and the silicon oxide film 3 and between thesilicon oxide film 3 and the protection film 4 is favorably achieved.

A preferred thickness of the protection film 4 is from 5,000 Å to 15,000Å, and a thickness of about 10,000 Å is preferred even more.

The wiring 6 is made of aluminum or an aluminum alloy. Examples of thealuminum alloy used include an alloy of aluminum, silicon, and copper,an alloy of aluminum and copper, and an alloy of aluminum and silicon.

A preferred thickness of the wiring 6 is from 3,000 Å to 30,000 Å, and athickness of about 5,000 Å is even more preferred.

The anti-reflection film 7 also functions as a wiring. Theanti-reflection film 7 is made of titanium nitride.

A preferred thickness of the anti-reflection film 7 is from 250 Å to 800Å, and a thickness of about 400 Å is even more preferred.

The metal nitride region 7 a containing fewer dangling bonds alsofunctions as a wiring along with the wiring 6 and the anti-reflectionfilm 7. The metal nitride region 7 a containing fewer dangling bonds maybe formed from a single layer of a metal nitride film or a layered filmincluding a plurality of layers of metal nitride films.

Examples of a metal nitride forming the metal nitride region 7 acontaining fewer dangling bonds include a titanium nitride, a tantalumnitride, a molybdenum nitride, and a tungsten nitride that are formed bya method described later. Titanium nitride can easily be formed by themethod described later, and is accordingly preferred as a metal nitrideforming the metal nitride region 7 a containing fewer dangling bonds.

[Method of Manufacturing Semiconductor Device]

(First Manufacturing Method)

A method of manufacturing a semiconductor device according to thepresent invention is described next by taking as an example a method ofmanufacturing the semiconductor device of FIG. 1. FIG. 2 to FIG. 6 areprocess views for illustrating an example of the method of manufacturingthe semiconductor device of FIG. 1.

To manufacture the semiconductor device 10 illustrated in FIG. 1, alaminate 5 which includes the interlayer insulating film 2, the wiring6, the anti-reflection film 7, and a metal nitride film 71, is firstformed on one of the principal surfaces of the substrate 1.

Specifically, the interlayer insulating film 2 is formed on thesubstrate 1 as illustrated in FIG. 2 by CVD or other methods. The wiring6 is then formed on the interlayer insulating film 2 by sputtering orother methods (a wiring step).

The anti-reflection film 7 is formed next from titanium nitride on thewiring 6 as illustrated in FIG. 3 by reactive sputtering that uses argongas (Ar) and nitrogen gas (N₂) (an anti-reflection film forming step).

The proportion of nitrogen gas to argon gas (Ar:N₂) to form theanti-reflection film 7 is, for example, from 1:2 to 1:5 in flow ratio,and about 3:7 is preferred. When the proportion of nitrogen (Ar:N₂) isequal to or higher than 1:2, titanium nitride forming theanti-reflection film 7 does not contain too many dangling bonds that arenot bonded to nitrogen. When the proportion of nitrogen (Ar:N₂) is equalto or lower than 1:5, the anti-reflection film 7 can be formed at asatisfactorily high film forming speed which gives the semiconductordevice 10 excellent productivity.

Next, the metal nitride film 71 is formed on the anti-reflection film 7by reactive sputtering in which the proportion of nitrogen gas to argongas is set higher than the proportion used when the anti-reflection film7 is formed (a step of forming a metal nitride film that contains fewerdangling bonds). The metal nitride film 71 containing fewer danglingbonds than dangling bonds of titanium atoms in the anti-reflection film7 is obtained by setting the proportion of nitrogen gas to argon gashigher than the proportion used when the anti-reflection film 7 isformed.

In the step of forming a metal nitride film that contains fewer danglingbonds, it is preferred to form a titanium nitride film as the metalnitride film 71 by reactive sputtering that uses a target containingtitanium. With this, it is possible to successively form theanti-reflection film 7 and the metal nitride film 71 with the use of thetarget used to form the anti-reflection film 7, which facilitates theforming of the metal nitride film 71.

The proportion of nitrogen gas to argon gas (Ar:N₂) to form a titaniumnitride film as the metal nitride film 71 is, for example, from 1:8 to1:10 in flow ratio, and about 1:9 is preferred. When the proportion ofnitrogen (Ar:N₂) is equal to or higher than 1:8, it is easy to obtain atitanium nitride film containing fewer dangling bonds of titanium atomsthat are not bonded to nitrogen. When the proportion of nitrogen (Ar:N₂)is equal to or lower than 1:10, the metal nitride film 71 can be formedat a satisfactorily high film forming speed, which gives thesemiconductor device 10 an excellent productivity.

In the step of forming a metal nitride film that contains fewer danglingbonds, a target containing one type of metal that is selected from thegroup consisting of tantalum, molybdenum, and tungsten may be used inplace of a target containing titanium. In this case, one type of metalnitride film that is selected from the group consisting of a tantalumnitride film, a molybdenum nitride film, and a tungsten nitride film canbe formed as the metal nitride film 71.

The proportion of nitrogen gas to argon gas (Ar:N₂) to form one of themetal nitride films given above as the metal nitride film 71 is, forexample, from 1:8 to 1:10 in flow ratio, and about 1:9 is preferred.When the proportion of nitrogen (Ar:N₂) is equal to or higher than 1:8,it is easy to obtain a metal nitride film containing fewer danglingbonds of metal atoms that are not bonded to nitrogen. When theproportion of nitrogen (Ar:N₂) is equal to or lower than 1:10, the metalnitride film 71 can be formed at a satisfactorily high film formingspeed, which gives the semiconductor device 10 an excellentproductivity.

Next, the wiring 6, the anti-reflection film 7, and the metal nitridefilm 71 are patterned into a given shape as illustrated in FIG. 4 withthe use of a known photolithography method and a known etching method.In the example illustrated in FIG. 1, a wiring layer which includes thewiring 6, the anti-reflection film 7, and the metal nitride film 71, isformed by patterning the wiring 6, the anti-reflection film 7, and themetal nitride film 71 into the same shape.

The silicon oxide film 3 is formed next on the wiring layer whichincludes the wiring 6, the anti-reflection film 7, and the metal nitridefilm 71, so as to cover the wiring layer as illustrated in FIG. 5 byplasma CVD or other methods (an oxide film forming step).

The protection film 4 is formed next on the silicon oxide film 3 asillustrated in FIG. 6 by plasma CVD or other methods (a protection filmforming step).

Next, a known photolithography method and a known etching method areused to form an opening that penetrates the protection film 4, thesilicon oxide film 3, the metal nitride film 71, and the anti-reflectionfilm 7, and exposes the wiring 6 at the bottom (an opening portionforming step). This forms the pad portion 8 which exposes the wiring 6,at a place where the first opening portion 91 which is formed in thesilicon oxide film 3, the second opening portion 92 which is formed inthe anti-reflection film 7, and the third opening portion 93 which isformed in the protection film 4, overlap with one another in plan viewas illustrated in FIG. 1.

Through the steps described above, the semiconductor device 10illustrated in FIG. 1 is obtained.

The method of manufacturing the semiconductor device 10 according to thefirst embodiment includes, after the anti-reflection film forming stepand before the oxide film forming step, a step of forming on theanti-reflection film 7 the metal nitride film 71 which contains fewerdangling bonds than in the anti-reflection film 7 by reactive sputteringin which the proportion of nitrogen gas to argon gas is set higher thanthe proportion used when the anti-reflection film 7 is formed. Thesemiconductor device 10 of FIG. 1 in which the metal nitride region 7 acontaining fewer dangling bonds is formed from the metal nitride film 71containing fewer dangling bonds than in the anti-reflection film 7 overthe entire opposed surface of the anti-reflection film 7 which faces thesilicon oxide film 3 above the anti-reflection film 7 is accordinglyobtained by executing the oxide film forming step and the openingportion forming step in the stated order after the step of forming themetal nitride film 71 containing fewer dangling bonds.

In addition, since the method of manufacturing the semiconductor device10 according to the first embodiment does not require an exposure stepfor forming the metal nitride region 7 a containing fewer danglingbonds, the metal nitride region 7 a containing fewer dangling bonds isformed efficiently and consequently gives the manufacturing methodexcellent productivity.

(Second Manufacturing Method)

The method of manufacturing the semiconductor device 10 of FIG. 1 is notlimited to the first manufacturing method described above, and thesemiconductor device 10 of FIG. 1 may be manufactured by, for example, asecond manufacturing method described below.

FIG. 7 and FIG. 8 are process views for illustrating another example ofthe method of manufacturing the semiconductor device of FIG. 1.

The second manufacturing method described below differs from the firstmanufacturing method in the step of forming a metal nitride film thatcontains fewer dangling bonds. Specifically, steps up through the stepof forming the anti-reflection film 7 on the wiring 6 (theanti-reflection film forming step) are carried out as illustrated inFIG. 7 in the second manufacturing method as in the first manufacturingmethod. Then, before the oxide film forming step, a titanium nitridefilm is formed on a surface of the anti-reflection film 7 as the metalnitride film 71 containing fewer dangling bonds as illustrated in FIG. 8by a nitridation process (the step of forming a metal nitride film thatcontains fewer dangling bonds).

The nitridation process in the step of forming a metal nitride film thatcontains fewer dangling bonds is preferred to be heat treatment in anitrogen-containing gas atmosphere, or plasma treatment that uses anitrogen-containing gas. A preferred nitrogen-containing gas to be usedin the nitridation process is nitrogen gas and/or ammonium gas, andnitrogen gas is particularly preferred.

Heat treatment in which the sample is held in a nitrogen-containing gasatmosphere at a temperature from 350° C. to 650° C. for about one minute(rapid thermal annealing: RTA) is an example of the heat treatment in anitrogen-containing gas atmosphere.

Treatment performed in a nitrogen-containing gas atmosphere with the useof a plasma etching device is an example of the plasma treatment.

The second manufacturing method described above includes, after theanti-reflection film forming step and before the oxide film formingstep, a step of forming a metal nitride film that contains fewerdangling bonds by performing a nitridation process on the surface of theanti-reflection film 7. The semiconductor device 10 of FIG. 1 in whichthe metal nitride region 7 a containing fewer dangling bonds is formedover the entire opposed surface of the anti-reflection film 7 whichfaces the silicon oxide film 3 above the anti-reflection film 7 isaccordingly obtained by executing the oxide film forming step and theopening portion forming step in the stated order after the step offorming a metal nitride film that contains fewer dangling bonds.

In addition, since the second manufacturing method does not require anexposure step for forming the metal nitride region 7 a containing fewerdangling bonds, the metal nitride region 7 a containing fewer danglingbonds is formed efficiently and consequently gives the secondmanufacturing method an excellent productivity.

The step of forming a metal nitride film that contains fewer danglingbonds in the second manufacturing method may be executed, if necessary,after the step of forming a metal nitride film that contains fewerdangling bonds in the first manufacturing method, before the oxide filmforming step.

In this case, a layered film that includes a film formed by the firstmanufacturing method and a film formed by the second manufacturingmethod is formed as the metal nitride film 71 on the anti-reflectionfilm 7.

<Second Embodiment>

[Semiconductor Device]

FIG. 9 is a schematic sectional view for illustrating another example ofthe semiconductor device according to the present invention.

A semiconductor device 20 according to a second embodiment of thepresent invention which is illustrated in FIG. 9 differs from thesemiconductor device 10 according to the first embodiment only in thelocation where the metal nitride region containing fewer dangling bondsis formed. Descriptions on the same members as those in thesemiconductor device 10 according to the first embodiment are thereforeomitted in the second embodiment.

In the semiconductor device 10 of FIG. 1, the metal nitride region 7 acontaining fewer dangling bonds is formed on the entire opposed surfaceof the anti-reflection film 7 which faces the silicon oxide film 3 abovethe anti-reflection film 7. In the semiconductor device 20 of FIG. 9, ametal nitride region 7 b containing fewer dangling bonds is formed onthe entire exposed surface of the anti-reflection film 7 which isexposed in the second opening portion 92.

The metal nitride region 7 b containing fewer dangling bonds can beformed of any metal nitride that contains fewer dangling bonds than inthe anti-reflection film 7, for example, a titanium nitride that isformed by a method described later.

[Method of Manufacturing Semiconductor Device]

A method of manufacturing the semiconductor device of FIG. 9 isdescribed next through an example. FIG. 10 to FIG. 13 are process viewsfor illustrating an example of the method of manufacturing thesemiconductor device of FIG. 9.

To manufacture the semiconductor device 20 of FIG. 9, steps up throughthe anti-reflection film forming step are executed first as when thesemiconductor device 10 of FIG. 1 is manufactured.

Next, a known photolithography method and a known etching method areused to pattern the wiring 6 and the anti-reflection film 7 into a givenshape as illustrated in FIG. 10. In the example illustrated in FIG. 9, awiring layer including the wiring 6 and the anti-reflection film 7 isformed by patterning the wiring 6 and the anti-reflection film 7 intothe same shape.

The silicon oxide film 3 is formed next on the wiring layer includingthe wiring 6 and the anti-reflection film 7 so as to cover the wiringlayer as illustrated in FIG. 11 by plasma CVD or other methods (an oxidefilm forming step).

The protection film 4 is formed next on the silicon oxide film 3 asillustrated in FIG. 12 by plasma CVD or other methods (a protection filmforming step).

Photolithography and etching are used next to form an opening thatpenetrates the protection film 4, the silicon oxide film 3, and theanti-reflection film 7, and exposes the wiring 6 at the bottom (in theexample of FIG. 13, the first opening portion 91, the second openingportion 92, and the third opening portion 93), as illustrated in FIG. 13(an opening portion forming step). This forms the pad portion 8 whichexposes the wiring 6, at a place where the first opening portion 91which is formed in the silicon oxide film 3, the second opening portion92 which is formed in the anti-reflection film 7, and the third openingportion 93 which is formed in the protection film 4, overlap with oneanother in plan view as illustrated in FIG. 13.

A nitridation process is performed next on a portion of theanti-reflection film 7 that is exposed in the second opening portion 92,which is a step of forming a metal nitride region that contains fewerdangling bonds. The exposed surface of the anti-reflection film 7 whichis exposed in the second opening portion 92 is thus turned into themetal nitride region 7 b containing fewer dangling bonds than in theanti-reflection film 7.

The nitridation process in the step of forming a metal nitride regionthat contains fewer dangling bonds can be performed in the same way aswhen the nitridation process is performed in the manufacturing steps ofthe semiconductor device 10 of FIG. 1.

Through the steps described above, the semiconductor device 20illustrated in FIG. 9 is obtained.

The method of manufacturing the semiconductor device 20 according to thesecond embodiment includes a step of forming a metal nitride region thatcontains fewer dangling bonds by performing a nitridation process on aportion of the anti-reflection film 7 that is exposed in the secondopening portion 92 after the opening portion forming step. Thesemiconductor device 20 of FIG. 9 in which the metal nitride region 7 bcontaining fewer dangling bonds is formed from a metal nitride filmcontaining fewer dangling bonds than in the anti-reflection film 7 overthe entire exposed surface that is exposed in the second opening portion92 is accordingly obtained after the step of forming a nitride regionthat contains fewer dangling bonds.

In addition, since the method of manufacturing the semiconductor device20 according to the second embodiment does not require an exposure stepfor forming the metal nitride region 7 b containing fewer danglingbonds, the metal nitride region 7 b containing fewer dangling bonds isformed efficiently and consequently gives the manufacturing method anexcellent productivity.

<Third Embodiment>

[Semiconductor Device]

FIG. 14 is a schematic sectional view for illustrating still anotherexample of the semiconductor device according to the present invention.

A semiconductor device 30 according to a third embodiment of the presentinvention which is illustrated in FIG. 14 differs from the semiconductordevice 10 according to the first embodiment only in the location wherethe metal nitride region containing fewer dangling bonds is formed.Descriptions on the same members as those in the semiconductor device 10according to the first embodiment are therefore omitted in the thirdembodiment.

In the semiconductor device 10 of FIG. 1, the metal nitride region 7 acontaining fewer dangling bonds is formed on the entire opposed surfaceof the anti-reflection film 7 which faces the silicon oxide film 3 abovethe anti-reflection film 7. In the semiconductor device 30 of FIG. 14, ametal nitride region 7 c containing fewer dangling bonds is formed onthe entire exposed surface of the anti-reflection film 7 which isexposed in the second opening portion 92, in addition to the entireopposed surface of the anti-reflection film 7 which faces the siliconoxide film 3 above the anti-reflection film 7.

The metal nitride region 7 c containing fewer dangling bonds may beformed from a metal nitride film of one type or from metal nitride filmsof a plurality of types. The metal nitride region 7 c containing fewerdangling bonds that is formed from metal nitride films of a plurality oftypes includes, for example, different metal nitride films used to formthe opposed surface of the anti-reflection film 7 which faces thesilicon oxide film 3 above the anti-reflection film 7, and the exposedsurface of the anti-reflection film 7 which is exposed in the secondopening portion 92.

Of the metal nitride region 7 c containing fewer dangling bonds, a metalnitride that forms the opposed surface of the anti-reflection film 7which faces the silicon oxide film 3 above the anti-reflection film 7,can be the same metal nitride that forms the metal nitride region 7 acontaining fewer dangling bonds in the semiconductor device 10 accordingto the first embodiment.

Of the metal nitride region 7 c containing fewer dangling bonds, a metalnitride that forms the exposed surface of the anti-reflection film 7which is exposed in the second opening portion 92, can be the same metalnitride that forms the metal nitride region 7 b containing fewerdangling bonds in the semiconductor device 20 according to the secondembodiment.

[Method of Manufacturing Semiconductor Device]

A method of manufacturing the semiconductor device of FIG. 14 isdescribed next through an example. To manufacture the semiconductordevice 30 of FIG. 14, the semiconductor device 10 according to the firstembodiment which is illustrated in FIG. 1 is manufactured first by oneof the first manufacturing method and the second manufacturing methodwhich are described above.

The next step is to form a metal nitride region that contains fewerdangling bonds in the semiconductor device 10 according to the firstembodiment which is illustrated in FIG. 1. This step is the same as thestep of forming a metal nitride region that contains fewer danglingbonds in the manufacture of the semiconductor device 20 according to thesecond embodiment. The opposed surface of the anti-reflection film 7which faces the silicon oxide film 3 above the anti-reflection film 7,and the exposed surface of the anti-reflection film 7 which is exposedin the second opening portion 92, are thus turned into the metal nitrideregion 7 c containing fewer dangling bonds and formed from a metalnitride film containing fewer dangling bonds than in the anti-reflectionfilm 7 as illustrated in FIG. 14.

Through the steps described above, the semiconductor device 30illustrated in FIG. 14 is obtained.

The method of manufacturing the semiconductor device 30 according to thethird embodiment includes a step of forming a metal nitride region thatcontains fewer dangling bonds by performing a nitridation process on aportion of the anti-reflection film 7 that is exposed in the opening ofthe semiconductor device 10 according to the first embodiment. Thesemiconductor device 30 of FIG. 14 is accordingly obtained in which themetal nitride region 7 c containing fewer dangling bonds is formed froma metal nitride film containing fewer dangling bonds than in theanti-reflection film 7 on the entire opposed surface of theanti-reflection film 7 which faces the silicon oxide film 3 above theanti-reflection film 7, and the entire exposed surface of theanti-reflection film 7 which is exposed in the second opening portion92.

In addition, since the method of manufacturing the semiconductor device30 according to the third embodiment does not require an exposure stepfor forming the metal nitride region 7 c containing fewer danglingbonds, the metal nitride region 7 c containing fewer dangling bonds isformed efficiently and consequently gives the manufacturing method anexcellent productivity.

The semiconductor device according to the present invention is notlimited to the semiconductor devices described above, namely, thesemiconductor device 10 according to the first embodiment, thesemiconductor device 20 according to the second embodiment, and thesemiconductor device 30 according to the third embodiment. For instance,the metal nitride region containing fewer dangling bonds only needs tobe formed in at least a part of one or both of the opposed surface ofthe anti-reflection film 7 which faces the silicon oxide film 3 abovethe anti-reflection film, and the exposed surface of the anti-reflectionfilm 7 which is exposed in the second opening portion 92.

The descriptions given above on the semiconductor device 10 according tothe first embodiment and the semiconductor device 30 according to thethird embodiment take as an example a case in which a single wiringlayer including the wiring 6, the anti-reflection film 7, and the metalnitride region containing fewer dangling bonds is included (the singlewiring layer in the second embodiment includes the wiring 6 and theanti-reflection film 7). However, one or more wiring layers containing aknown material may be included in addition to the wiring layer describedabove. When the semiconductor device according to the present inventionincludes a plurality of wiring layers, it is preferred that the wiringlayer including the wiring 6, the anti-reflection film 7, and the metalnitride region containing fewer dangling bonds (in the secondembodiment, the wiring layer including the wiring 6 and theanti-reflection film 7) be the topmost wiring layer.

The semiconductor device according to the present invention may furtherinclude layers having various functions to suit its use.

EXAMPLE

Now, effects of the present invention are further clarified from thedescription of examples of the present invention. The present inventionis not limited to the following examples, and modifications can be madethereto as appropriate within the range not changing the gist of thepresent invention.

Example 1

A semiconductor device of Example 1 illustrated in FIG. 1 was obtainedby a manufacturing method described below.

First, the interlayer insulating film 2 was formed from a SiO₂ film onthe substrate 1 made of silicon as illustrated in FIG. 2 by CVD. Thewiring 6 made of an alloy of aluminum, silicon, and copper and having athickness of 5,000 Å was then formed on the interlayer insulating film 2by sputtering (the wiring step).

The anti-reflection film 7 made of titanium nitride and having athickness of 400 Å was formed next on the wiring 6 as illustrated inFIG. 3 by reactive sputtering that used a target containing titanium andargon gas (Ar) and nitrogen gas (N₂) (the anti-reflection film formingstep). The proportion of nitrogen gas to argon gas (Ar:N₂) to form theanti-reflection film 7 was set to 3:7 in volume ratio.

The metal nitride film 71 was formed next from a titanium nitride filmon the anti-reflection film 7 by reactive sputtering in which theproportion of nitrogen gas to argon gas (Ar:N₂) was set to 1:9 in volumeratio (the step of forming a metal nitride film that contains fewerdangling bonds). The anti-reflection film 7 and the metal nitride film71 were formed successively.

Next, the wiring 6, the anti-reflection film 7, and the metal nitridefilm 71 were patterned as illustrated in FIG. 4 with the use ofphotolithography and etching to form the wiring layer including thewiring 6, the anti-reflection film 7, and the metal nitride film 71.

The silicon oxide film 3 having a thickness of 2,000 Å was formed nextfrom a SiO₂ film on the wiring layer including the wiring 6, theanti-reflection film 7, and the metal nitride film 71 as illustrated inFIG. 5 by plasma CVD so as to cover the wiring layer (the oxide filmforming step).

The protection film 4 was formed next from a silicon nitride film on thesilicon oxide film 3 as illustrated in FIG. 6 so as to have a thicknessof 7,000 Å by plasma CVD (the protection film forming step).

Photolithography and etching were used next to form an opening thatpenetrated the protection film 4, the silicon oxide film 3, the metalnitride film 71, and the anti-reflection film 7, and exposed the wiring6 at the bottom (the opening portion forming step), thereby forming thepad portion 8.

Through the steps described above, the semiconductor device 10 ofExample 1 illustrated in FIG. 1 was obtained.

Example 2

A semiconductor device 10 of Example 2 was obtained in the same way asin Example 1, except that the following step of forming a metal nitridefilm that contains fewer dangling bonds was performed in place of thestep of forming a metal nitride film that contains fewer dangling bondsin the manufacture of the semiconductor device 10 of Example 1.

In Example 2, a nitridation process was performed on a surface of theanti-reflection film 7 as the step of forming a metal nitride filmcontaining fewer dangling bonds. Heat treatment in which the sample washeld in a nitrogen gas atmosphere at 350° C. for one minute wasperformed as the nitridation process.

Example 3

A semiconductor device of Example 3 which is illustrated in FIG. 9 wasobtained by the following manufacturing method.

Steps up through the anti-reflection film forming step were executed inthe same way as in Example 1. Next, photolithography and etching wereused to pattern the wiring 6 and the anti-reflection film 7 asillustrated in FIG. 10, thereby forming a wiring layer including thewiring 6 and the anti-reflection film 7.

The silicon oxide film 3 and the protection film 4 were formed next inthe stated order on the wiring layer including the wiring 6 and theanti-reflection film 7, in the same way as in Example 1.

Photolithography and etching were used next to form an opening thatpenetrated the protection film 4, the silicon oxide film 3, and theanti-reflection film 7, and exposed the wiring 6 at the bottom (theopening portion forming step), thereby forming the pad portion 8.

Next, the same nitridation process as the nitridation process in thestep of forming a metal nitride film that contains fewer dangling bondsin Example 2 was performed on a portion of the anti-reflection film 7that was exposed in the second opening portion 92, to thereby obtain thesemiconductor device 20 of Example 3, which is illustrated in FIG. 9.

Example 4

A semiconductor device 30 of Example 4 which is illustrated in FIG. 14was obtained by performing, on the semiconductor device 10 of Example 1,the same nitridation process as the nitridation process that wasperformed in the step of forming a metal nitride film that containsfewer dangling bonds in the manufacture of the semiconductor device 20of Example 3.

Comparative Example 1

A semiconductor device of Comparative Example 1 was obtained in the sameway as in Example 1, except that the step of forming a metal nitridefilm that contains fewer dangling bonds was not executed.

The thus obtained semiconductor devices of Examples 1 to 4 andComparative Example 1 were subjected to the following long-termreliability test (THB) involving bias application under ahigh-temperature and high-humidity environment, and the appearancesthereof were evaluated.

“Long-term Reliability Test (THB)”

The semiconductor devices of Examples 1 to 4 and Comparative Example 1were each packaged into a package to create twenty-two samples for eachsemiconductor device. A voltage was applied to each sample for 1,000hours in an environment in which the temperature was 85° C. and thehumidity (RH) was 85%. Each package was then opened, and a portionaround the pad portion was observed under a microscope to conduct anappearance test by the following criteria.

“Criteria”

Appearance is fine: there is no corrosion, detachment, or discolorationin the pad portion or around the pad portion.

Appearance is defective: corrosion, detachment, or discoloration isfound in the pad portion or around the pad portion.

After the long-term reliability test (THB), the numbers of defectiveappearance samples in the semiconductor devices of Examples 1 to 4 andComparative Example 1 were as follows. Specifically, the number ofdefective appearance samples (the number of defective appearancesamples/the total number of samples) was 0/22 in Example 1 to Example 4each, and the number of defective appearance samples (the number ofdefective appearance samples/the total number of samples) was 3/20 inComparative Example 1.

As a result of the long-term reliability test (THB), the semiconductordevices of Examples 1 to 4 were found to be higher in reliability thanthe semiconductor device of Comparative Example 1. The higherreliability is inferred to be the result of the prevention of theoxidation of titanium nitride forming the anti-reflection film by thepresence of the metal nitride region containing fewer dangling bondswhich was formed in the semiconductor devices of Examples 1 to 4.

Of the semiconductor devices of Examples 1 to 4, the semiconductordevice of Example 4 in which a metal nitride region containing fewerdangling bonds than in the anti-reflection film is formed on both of theentire opposed surface of the anti-reflection film 7 which faces thesilicon oxide film 3 above the anti-reflection film 7, and the entireexposed surface of the anti-reflection film 7 which is exposed in thesecond opening portion 92, is considered to be particularly high inreliability, although the semiconductor device of Example 4 is notdifferent from the semiconductor devices of Examples 1 to 3 in thislong-term reliability test.

What is claimed is:
 1. A method of manufacturing a semiconductor device,comprising: forming a wiring on a substrate; forming an anti-reflectionfilm from titanium nitride on the wiring by reactive sputtering thatuses argon gas and nitrogen gas; forming a metal nitride film thatcontains fewer dangling bonds than in the anti-reflection film on theanti-reflection film by reactive sputtering in which a proportion ofnitrogen gas to argon gas is set higher than a proportion of nitrogengas to argon gas that is used when the anti-reflection film is formed;forming a silicon oxide film on the metal nitride film containing fewerdangling bonds than in the anti-reflection film; and forming an openingthat penetrates the silicon oxide film, the metal nitride filmcontaining fewer dangling bonds than in the anti-reflection film, andthe anti-reflection film, and that exposes the wiring at a bottom of theopening.
 2. The method of manufacturing a semiconductor device accordingto claim 1, wherein the step of manufacturing a metal nitride film thatcontains fewer dangling bonds than in the anti-reflection film includesforming a titanium nitride film by reactive sputtering that uses atarget containing titanium.
 3. A method of manufacturing a semiconductordevice, comprising: forming a wiring on a substrate; forming ananti-reflection film from titanium nitride on the wiring; forming ametal nitride film that contains fewer dangling bonds than in theanti-reflection film by performing a nitridation process on a surface ofthe anti-reflection film; forming a silicon oxide film on the metalnitride film containing fewer dangling bonds than in the anti-reflectionfilm; and forming an opening that penetrates the silicon oxide film, themetal nitride film containing fewer dangling bonds than in theanti-reflection film, and the anti-reflection film, and that exposes thewiring at a bottom of opening.
 4. The method of manufacturing asemiconductor device according to claim 3, wherein the nitridationprocess is one of heat treatment in a nitrogen-containing gas atmosphereand plasma treatment that uses a nitrogen-containing gas.
 5. The methodof manufacturing a semiconductor device according to claim 1, furthercomprising a protection film forming step of forming a protection filmfrom a silicon nitride film on the silicon oxide film after the oxidefilm forming step, wherein the opening portion forming step includesforming the opening that penetrates the protection film and exposes thewiring at the bottom.
 6. The method of manufacturing a semiconductordevice according to claim 2, further comprising a protection filmforming step of forming a protection film from a silicon nitride film onthe silicon oxide film after the oxide film forming step, wherein theopening portion forming step includes forming the opening thatpenetrates the protection film and exposes the wiring at the bottom. 7.The method of manufacturing a semiconductor device according to claim 3,further comprising a protection film forming step of forming aprotection film from a silicon nitride film on the silicon oxide filmafter the oxide film forming step, wherein the opening portion formingstep includes forming the opening that penetrates the protection filmand exposes the wiring at the bottom.